''Pachyrukhos'' is an extinct genus of hegetotheriid notoungulate from the Early to

Middle Miocene The Middle Miocene is a sub-epoch of the Miocene epoch (geology), epoch made up of two Stage (stratigraphy), stages: the Langhian and Serravallian stages. The Middle Miocene is preceded by the Early Miocene. The sub-epoch lasted from 15.97 ± 0. ...

( Colhuehuapian- Friasian in the SALMA classification) of

Argentina Argentina, officially the Argentine Republic, is a country in the southern half of South America. It covers an area of , making it the List of South American countries by area, second-largest country in South America after Brazil, the fourt ...

and

Chile Chile, officially the Republic of Chile, is a country in western South America. It is the southernmost country in the world and the closest to Antarctica, stretching along a narrow strip of land between the Andes, Andes Mountains and the Paci ...

. Fossils of this genus have been found in the Collón Curá,

Sarmiento Sarmiento may refer to: Places Argentina *Sarmiento Department, San Juan, a subdivision of the San Juan Province * Sarmiento Department, Santiago del Estero, a subdivision of the Santiago del Estero Province * Sarmiento Department, Chubut, a subdi ...

and

Santa Cruz Formation The Santa Cruz Formation is a geological formation in the Magallanes Basin, Magallanes/Austral Basin in southern Patagonia in Argentina and adjacent areas of Chile. It dates to the late Early Miocene epoch, and is contemporaneous with the eponym ...

s of Argentina and the Río Frías Formation of Chile.''Pachyrukhos''
at

Fossilworks Fossilworks was a portal which provides query, download, and analysis tools to facilitate access to the Paleobiology Database, a large relational database assembled by hundreds of paleontologists from around the world. History Fossilworks was cr ...

.org

Description

It was about long and closely resembled a

rabbit Rabbits are small mammals in the family Leporidae (which also includes the hares), which is in the order Lagomorpha (which also includes pikas). They are familiar throughout the world as a small herbivore, a prey animal, a domesticated ...

, with a short tail and long hind feet. ''Pachyrukhos'' was probably also able to hop, and it had a rabbit-like

skull The skull, or cranium, is typically a bony enclosure around the brain of a vertebrate. In some fish, and amphibians, the skull is of cartilage. The skull is at the head end of the vertebrate. In the human, the skull comprises two prominent ...

with teeth adapted for eating nuts and tough plants. The complexity of its hearing apparatus in the skull suggests that its

hearing Hearing, or auditory perception, is the ability to perceive sounds through an organ, such as an ear, by detecting vibrations as periodic changes in the pressure of a surrounding medium. The academic field concerned with hearing is auditory sci ...

would have been very good, and that it probably had large ears. It also had large eyes, suggesting that it may have been nocturnal. These similarities are the result of

convergent evolution Convergent evolution is the independent evolution of similar features in species of different periods or epochs in time. Convergent evolution creates analogous structures that have similar form or function but were not present in the last comm ...

, since, while quite unrelated to modern rabbits, ''Pachyrukhos'' filled the same

ecological niche In ecology, a niche is the match of a species to a specific environmental condition. Three variants of ecological niche are described by It describes how an organism or population responds to the distribution of Resource (biology), resources an ...

References

Typotheres Miocene mammals of South America Friasian Santacrucian Colhuehuapian Neogene Argentina Fossils of Argentina Neogene Chile Fossils of Chile Fossil taxa described in 1885 Taxa named by Florentino Ameghino Prehistoric placental genera Austral or Magallanes Basin Golfo San Jorge Basin Santa Cruz Formation Sarmiento Formation {{notoungulate-stub